Ding is careless with the c2-bishop. He certainly miscalculated something.
16. f4h2 White's plan is to play f3-e4. 16... g8h8 Great efficiency from the rook. Having done its job on the g8, it's time to go back to an open file. 17. f2f3 Another innacuracy. 17... h5g7  18. h2g3 The critical moment in the game.